Barack Obama infamously said that he would govern by a “pen and a phone.” He has circumvented Congress and the laws for years. The Democrats (and much of the media, but I repeat myself) have not only given him a pass, but cheered him on. Now it appears a seldom-noticed law might be a powerful tool that Trump can use to eviscerate much of the Obama legacy.

Dozens of major regulations passed recently by the Obama administration — including far-reaching changes on health care, consumer protections and environmental safety — could be undone with the stroke of a pen by Donald J. Trump and the Republican-controlled Congress starting in January, thanks to a little-used law that dates back to 1996.

And it comes with a scorched-earth kicker: If the law is used to strike down a rule, the federal agency that issued it is barred from enacting similar regulation again in the future.

The obscure law — called the Congressional Review Act — was passed 20 years ago at the behest of Newt Gingrich, then the House speaker and now a member of Mr. Trump’s transition team. It gives Congress 60 legislative days to review and override major regulations enacted by federal agencies. In the Senate, the vote would not be subject to filibuster.

The president can veto the rejection, which usually renders the law toothless. But when one party controls both the White House and Congress, it can be a powerful legislative weapon.

So far it has only been successfully used once: In 2001, a Republican Congress invoked it to eliminate workplace safety regulations adopted in the final months of President Clinton’s tenure. President George W. Bush signed the repeal two months after his inauguration, wiping out stricter ergonomics rules that had been 10 years in the making.

On Jan. 20, when Mr. Trump takes office with a Republican-controlled Congress — one that has indicated its zeal for undoing President Obama’s doings — more than 150 rules adopted since late May are potentially vulnerable to the ax, according to an analysis by the George Washington University Regulatory Studies Center.

“It allows the election results to be applied almost retroactively, to snip off activity that happened at the end of the last administration,” said Adam Levitin, a law professor at Georgetown.

The column notes several examples of rules and regulations Obama’s White House has been quickly rolling out in the dying months of his presidency. However, there is a new sheriff in town.

The GOP House has been trying to use this law for years but was stymied by Obama’s veto power.

Under Speaker Paul D. Ryan’s leadership, the House has used the law several times to try to reject a number of the Obama administration’s policies. Those challenges were symbolic — President Obama vetoed every one that reached his desk — but President-elect Trump can approve any sent to him after he takes office. Mr. Ryan’s office did not respond to requests for comment.

“I don’t think they’ll go after every single rule, but I think you’ll get eight to 10 that may be targeted,” said Sam Batkins, the director of regulatory policy at the American Action Forum, a right-leaning group that has been tracking which regulations are subject to congressional review.

The threat posed by the law may slow the usual rush of “midnight regulations” that administrations typically race to finish in their final days. This year, it will be a high-stakes game of chicken — put out a rule and hope it survives, or hold off, to preserve the chance to revisit it in the future?

House Republicans have already put bureaucrats on notice that efforts by them to slip through new rules and regulations will be met with extra scrutiny when a new Congress and president take charge in January. Lisa Rein of the Washington Post:

Newly empowered House Republicans on Tuesday laid down the gauntlet to the outgoing Obama administration: Don’t finalize any pending rules and regulations you think you can slip through before you leave office.

In a letter to hundreds of Cabinet secretaries, commissioners and other heads of federal offices and agencies signed by 22 Republican leaders, the lawmakers noted that President Obama has been generous in his use of executive orders to set policy. And they issued a threat: Ignore us and we will give your agency extra scrutiny.

“Should you ignore this counsel, please be aware that we will work with our colleagues to ensure that Congress scrutinizes your actions — and, if appropriate, overturns them …” said the one-paragraph missive signed by House Majority Leader Kevin McCarthy (R-Calif.) and 21 Republican committee heads. They oversee federal agencies from the Department of Veterans Affairs to the Environmental Protection Agency.

When liberals wail about this missive, they can be reminded that Obama’s team issued the same type of message. This warning should serve as a red line that bureaucrats will not cross and that Republicans will enforce.

In any case, Trump can go to DEFCON-4 on his own.

People on the right and among libertarians and freedom-seekers everywhere have long decried the rise of the regulatory state and its unchecked power in the hands of bureaucrats who have, seemingly, lifetime tenure and powers to wreak havoc on the economy.

Thomas Lifson has written about the pressing need to overhaul civil service rules to make the government and its worker bees more efficient, as has Bruce Walker in another American Thinker column. Bureaucrats are unelected and unaccountable officials who control too much power in America. Barack Obama has spent the last eight years implanting partisan true believers throughout the federal government. Many have been cleverly transforming themselves from political appointees, who can be relatively easily swept away when the Washington Stables are cleaned, to civil service employees who have all but lifetime tenure (this system is truly rigged and needs to be “fundamentally transformed”).

The power that the Congressional Review Act gives Donald Trump can accelerate the changes America needs to grow its economy from the stultifying burdens of Leviathan.

Trump has a pen and a phone, too. Democrats will soon be reminded of that phrase and come to rue it.